1. Field of the Invention
This invention relates to a rotor of a flat-type motor and more particularly to a rotor of a flat-type electric motor wherein a coil is wound in a flat space to form an armature coil. This invention is a continuation-in-part of our previous U.S. Pat. application Ser. No. 342,412, now U.S. Pat. No. 3,863,336, for a rotor of flat-type motor and method of manufacturing the same filed Mar. 19, 1973.
2. Description of the Prior Art
A print motor has been known as one of flat-type motors having small length in the axial direction. In the actually used print motors, there are more motors in which the armature circuit is formed by arranging conductive pieces and insulating materials alternately and connecting by welding the ends of the conductive pieces than motors in which the armature circuit is formed by print wiring. In such a print motor, the conductive pieces are not accumulated on an insulating plate but arranged laterally at equal intervals. Therefore, the length in the axial direction of the rotor is equal to the sum of the thickness of the insulating plate and the thickness twice as large as the thickness of the conductive pieces. Thus, the construction of the rotor is made extremely thin. The print motor of this type has a good response because the moment of inertia is small, and accordingly is commonly used as a servomotor.
On the other hand, the feature of flat-type motors having a flat appearance characterizes the use of the flat-type motors in comparison with general cup-like magnet motor. In practice, there are many cases wherein the flat type motors are preferred from the viewpoint of design and saving of space, for example in case of motors for blowers employed in air conditioners or cooling and heating apparatus for automobiles. For instance, in case of blowers for car heaters or car air conditioners generally comprising a sirocco fan and a cup-shaped motor, it becomes difficult to mount the blower to the engine room if the axial length of the blower becomes too long. In general, therefore, it has been common to form a recessed boss on the fan on the opposite side to the motor thereof and make a part of the motor mated with the recessed portion of the inside of the fan to save the space occupied by the blower. This construction, however, hinders smooth air flow within the fan and decreases the effective cross section of the fan and lowers the fan efficiency. If the motor is made flat in shape, the axial length thereof is markedly short and the outer diameter of the motor may be smaller than the outer diameter of the fan, and accordingly, the blower can be made compact as a whole and there is no need to decrease the effective cross section of the fan.
However, print motors have not been put into practical use in the above mentioned field for the following reasons. The first reason is that the print motor is disadvantageous from the viewpoint of noise, vibration, life and so forth. This is because a part of the armature coil serves as a commutator and is subject to brush pressure in the axial direction, and accordingly, the armature is comparatively weak in comparison with the general cup-shaped magnet motor and high accuracy in processing the commutator cannot be expected, and the commutator portion is deformed during revolution due to the brush pressure, the brush touch to the coil is affected by thrust, and the number of commutator segments is too many. Further, although the commutator surface can be easily made parallel to the shaft in a print motor by forming an armature coil and a commutator portion separately and connecting the both electrically, it is impractical and cannot be put into practical use due to its low work efficiency. The second reason is that the print motor cannot be easily manufactured satisfying various motor dimensions. This is because the armature circuit portion is processed by punching and the like and accordingly a large number of motors of the same dimension can be advantageously manufactured, but it is impractical to manufacture certain amount of motors of various dimensions since a great cost and long time is necessary to prepare the different molds. For example, in case of motors to be used for cooling and heating apparatus for automobiles, various dimensions are required to comply with various types of car models and various requirements of customers and the number of the respective dimensions is not always properly large.
In addition to the above described flat-type motors, it has been known in the art to directly wind a coil on a disc and mold it with a resin into an integrated unit, or to wind a coil on a pin fixed to a resinous disc and heat and press it to bury the coil into the disc to form a rotor. There has been no method of making flat-type rotors which is practical in efficiency of production, performance, and manufacturing cost.